Rotary hook for sewing machines



May 21, 1963 L. BONO 3,090,335

ROTARY HOOK FOR SEWING MACHINES Filed July 11, 1960 INVENTOR. L u l6!Bouo BY M mwmwuzm A'TT DEN 5Y5 United States Patent 3,090,335 ROTARYHGDK FUR SEWING MACHINES Luigi Bono, Pavia, Italy, assignor to N ecclriSocieta per Azioni, Pavia, Italy Filed July 11, 1960, Ser. No. 41,839Claims priority, application Italy July 20, 1959 7 Claims. (Cl. 112231)The invention relates in general to new and useful improvements inrotary hooks for double-thread lockstitch sewing machines, and moreparticularly to novel means for connecting a bobbin case holder ring tothe body of a rotary hook.

The primary object of the invention is to provide a novel means forreleasably fastening a bobbin case holder ring to a rotary hook bodywherein the bobbin case holder ring may be readily released or securedin place without utilizing fasteners such as screws or the like whichrequire the use of a screwdriver or other tools.

Another object of the invention is to provide a novel connection betweena bobbin case holder ring and a rotary hook body wherein the bobbin caseholder ring is readily released and engaged and wherein a fastenerassociated with the rotary hook body and engaged with the bobbin caseholder ring is utilized, the fastener being rotatable relative to boththe rotary hook body and the bob bin case holder ring to release orengage the bobbin case holder ring.

Still another object of the invention is to provide a simple releasableconnection between a rotary hook body and a bobbin case holder ringwhich employs a fastener associated with the rotary hook body and notrequiring modification of the rotary hook body or the formation ofopenings therein.

A further object of the invention is to provide releasable connectionsbetween a drive shaft, a rotary hook body and a bobbin case with theconnections employing simple contact between various components andutilizing a single screw to releasably secure the rotary hook body tothe drive shaft.

The invention is characterized by a bobbin case holder ring releasablyconnected to a rotary hook body by a locking member disposed coaxiallyto the hotary hook body and rotatable about the axis of the rotary hookbody while holding the bobbin case holder ring stationary to release andengage the bobbin case holder ring.

With the above, and other objects in View that will hereinafter appear,the nature of the invention will be more clearly understood by referenceto the following detailed description, the appended claims and theseveral views illustrated in the accompanying drawing:

In the drawing:

FIGURE 1 is an elevational view of the rotary hook assembly in a normalsewing position.

FIGURE 2 is an elevational view similar to FIGURE 1, and shows therotary hook assembly rotated to a bobbin case holder ring releasingposition.

FIGURE 3 is a plan view of the rotary hook assembly of FIGURE 1.

FIGURE 4 is an exploded perspective view of the components of the rotaryhook assembly.

FIGURE 5 is a fragmentary vertical sectional view through the rotaryhook assembly with the bobbin case and the bobbin case holder ringomitted, and shows the details of the fastening means.

Reference is now made to the several figures of the drawing wherein therotary hook body is referred to by the numeral 1 and the rotary threadgrasping hook is referred to by the numeral 2. The usual sewing machineis provided with a small drive shaft 3 which is suitably mounted forrotation and driven in a manner not shown. The

shaft 3 has a terminal flange 3 on which the body 1 seats with the body1 being held in place by a screw 4 passing through the body 1 andthreaded into the end of the shaft 3 through the flange 3'. Relativerotation of the body 1 with respect to the shaft 3 is prevented by a pin5 on the body 1 and engaged in a socket 6 in the flange 3'.

The rotary hook body 1 has an internal circumferential guide portion 7which is partially closed by a bobbin case holding ring 8 to define athroat in which is seated a peripheral edge portion 9 of a bobbin case10. The bobbin case 10 receives a customary bobbin 11.

At this time, it is pointed out that the hook 2, instead of being partof the body 1, could constitute an end of the bobbin case holder ring 8.Also, the bobbin 11, instead of being housed directly within the bobbincase 10, could be contained in a bobbin holding capsule (not shown)which, in turn, could be mounted in the bobbin case 10. This latterarrangement could be usefully employed when the hook has a horizontalaxis in lieu of a vertical axis, as is shown in the drawing, withoutgoing beyond the broad concept of the invention.

The bobbin case holder ring 8 is centered with respect to the body 1 bytwo short depending pins 12, 12 which are received in seats 13, 14,respectively, in the upper surface of the body 1. The pins 12, 12' alsoprevent rotation of the bobbin case holder ring 8 relative to the body1.

The body 1 has a lower portion in the form of a bushing 1 on which thereis mounted an elastic washer 15 and a coaxial flanged ring 16 in whichthe washer 15 is seated. The ring 16 is seated on the flange 3, and thewasher 15 is clamped between the ring 16 and the underside of the body 1to frictionally hold the ring 16 against rotation relative to the body1.

The ring 16 may be rotated a limited amount around the body 1 with therotation of the ring 16 being limited by the engagement of upstandingends 17, 18 thereof with ends 19, 20, respectively, of a needleprotector plate 21 which is removably secured to the body 1 by means ofscrews 22, 23. It is to be understood that within the scope of theinvention, the rotation of the ring 16 with respect to the body 1 couldbe accomplished by another look and slot means. The outer peripheralsurface of the ring 16 may be suitably contoured, such as by knurling,to facilitate the turning thereof.

The elastic washer 15 has a plurality of circumferentially spacedfingers 24 which are seated in notdhes 25 formed in the ring 16'. Inthis manner, the washer 15 is interlocked with the ring 16 for rotationtherewith.

The fingers 24 of the washer 15 are provided with upper inturned ends26. The inturned ends 26 engage the bobbin case holder ring 8 to retainthe same in place with the bobbin case iholder ring 8 engaging the edgeportion 9 of the bobbin case 10 to hold the bobbin case in place in thebody 1. The bobbin case holder ring 8 has axial outer grooves 27 of across-section and spacing to permit the passage of the finger ends 26. Astep 27' is disposed in circumferentially adjacent relation to each ofthe grooves 27 for engagement by the finger ends 26 to retain the bobbincase holder ring 8 in place on the body 1. The finger ends 26 and thesteps 27 are complementarily shaped to assure a perfect mutual coupling.

The elasticity of the washer 15 not only makes it possible for thefinger ends 26 to move over the steps 27' and thus assure an axial loadsuificient to guarantee the connection of the bobbin case holder ring 8to the body 1, but also to permit separation of the bobbin case holderring 8 from the body 1 in the case of interpositioning of foreignelements between these parts which otherwise might rigidly block anddamage the sewing machine.

From the foregoing, it is readily apparent that the releasing of thebobbin case holder ring 8 for the removal of the bobbin case is effectedby the rotation of the ring 16 in a direction opposite to the directionindicated by the arrow a in- FIGURE 3 While the shaft 3 is heldstationary by other components of the sewing machine. As' pointed outabove, the ring 16 is knurled to facilitate the rotation thereof. Afterthe rotation of the ring 16 has been efiected,'the finger ends 26 of theelastic Washer no longer engage the steps27', but are aligned 'with thegrooves 27. The bobbin case holder ring 8 may now be removed and thebobbin case Ibis free for removal to'permit the changing of the bobbin11.

After the bobbin case bolder ring b and bobbin case it) have beenremoved, the position of the ring 16 relative to the body 1, as shown inFIGURE 2, is maintained by the frictional engagement of the ring 16 withthe flange 3' due to the pressure exerted by the elastic Washer 15,which frictional engagement is sufiicient to prevent relative rotationof the bobbin case holder ring 8 and the body 1. This is useful in thesubsequent assembling of these parts.

When assembling the parts, the bobbincase 10 is positioned within'tliebody 1 with an appendage 28 thereof engaged in a recess 29 in a part 30which is fastened to the base of the sewing machine. The bobbin caseholder ring 8 is then mounted on the body 1 with the pins 12, i2engaging inthe seats 13 and 14, respectively, after which the ring 16 isrotated in the direction of the arrow a, while retaining the shaft 3against rotation, to engage the finger ends 26 with the steps 27 andlock the bobbin ease holder ring in place.

From the foregoing, it will be seen that novel and advantageousconstruction has been disclosed for attaining the desired ends. However,it is to be understood that numerous variations may be made Within thescope of the invention as defined in the appended claims.

What is claimed as new:

1. In a rotary hook assembly of the type including a shaft and a rotaryhook body secured to the shaft, a bobbin case seated insaid rotary bookbody, a bobbin case holder ring seated on said rotary book body. andretaining, said bobbin case therein, said bobbin case holder ring havingcircumferentially spaced seats, and a fastener connected to saidrotaryhook body having fingers extending :up alongside said bobbin case holderring and terminating in ends releasably. engaging said seats, saidbobbin case holder ring having finger end receiving grooves disposed in:eircumferent-ially spaced relation to said seats, whereby said bobbincase holder ring may be released by rotating said-fastener, saidfastener having a base portion resiliently clamped between said rotaryhook body and said shaft.

2. In a rotary hook assembly of the type including a shaft andya rotaryhook body secured to the shatt, a bobbin case seated in said rotary hookbody, a bobbin case bolder ringseated on said rotary hook body andretaining said bobbin case therein, said bobbin case holder ring havingcircurnierentially spaced seats, and a fastener connected to said rotaryhook body having fingers extending up alongside said bobbin case holderring and terminating in ends releasably engaging said seats, said bobbincase holder ring having finger end receiving grooves disposed incircumferentially spaced relation to said seats, whereby said bobbincase holder ring may be released by rotating said fastener, and aretaining ring receiving said fastener and interlocked therewith tofacilitate the rotation of said fastener.

3. In a rotary hook assembly of the type including a shaft and a rotaryhook body secured to the shaft, a bobbin case seated in said rotary hookbody, a bobbin case holder ring seated on said rotary hook body andretaining said bobbin case therein, said shaft having an upper endportion spaced from the underside of said rotary hook body, a cup-likeretaining ring surrounding said rotary hook body and seated on saidshaft end por tion, a fastener seated within said retaining ring andclamped between said retaining ring and said rotary hook body, saidfastener having circumierentially spaced upstanding fingers terminatingininturned ends engaging over and retaining said bobbin holder ring inplace.

4. In a rotary hook assembly of the type including a shaft and a rotaryhook body secured to the shaft, a bobbin case seated in said rotary hookbody, a bobbin case holder ring seated on said rotary hook body andretaining said bobbin case therein, said shaft having an upper endportion spaced from the underside of said rotary hook body, a cup-likeretaining ring surrounding said rotary hook body and seated on saidshaft end portion, a fastener seated Within said retaining ring andclamped between said retaining ring and said rotary hook body, saidfastener having circumferentially' spaced upstanding fingers terminatingin intnrned ends engaging over and retaining said bobbin case holderring in place, said bobbin case holder ring having spaced seats and saidfinger ends correspond to and engage said seats.

5. The assembly of claim 4 wherein said bobbin case holder ring hasfinger end receiving grooves disposed in circumferentially adjacentrelation to said seats, whereby said bobbin case holder ring may bereleased by rotating said fastener.

6. The assembly of claim 4 wherein said bobbin case holder ring hasfinger end receiving grooves disposed in ciroumferentially adjacentrelation tosaid sea-ts, whereby said bobbin case holder ring may bereleased by rotating said ifiastener, said retaining ring beinginterlocked with said fingers to facilitate rotation of said fastenerbetween a seat engaging position and a released position and return.

7. The assembly ofclairn 4 wherein said iiastener is of the elastic typeandsaid finger ends compressively engage said seats.

References Cited in the file of this patent UNITED STATES PATENTS

1. IN A ROTARY HOOK ASSEMBLY OF THE TYPE INCLUDING A SHAFT AND A ROTARYHOOK BODY SECURED TO THE SHAFT, A BOBBIN CASE SEATED IN SAID ROTARY HOOKBODY, A BOBBIN CASE HOLDER RING SEATED ON SAID ROTARY HOOK BODY ANDRETAINING SAID BOBBIN CASE THEREIN, SAID BOBBIN CASE HOLDER RING HAVINGCIRCUMFERENTIALLY SPACED SEATS, AND A FASTENER CONNECTED TO SAID ROTARYHOOK BODY HAVING FINGERS EXTENDING UP ALONGSIDE SAID BOBBIN CASE HOLDERRING AND TERMINATING IN ENDS RELEASABLY ENGAGING SAID SEATS, SAID BOBBINCASE HOLDER RING HAVING FINGER END RECEIVING GROOVED DISPOSED INCIRCUMFERENTIALLY SPACED RELATION TO SAID SEATS, WHEREBY SAID BOBBINCASE HOLDER RING MAY BE RELEASED BY ROTATING SAID FASTENER, SAIDFASTENER HAVING A BASE PORTION AND RESILIENTLY CLAMPED BETWEEN SAIDROTARY HOOK BODY AND SAID SHAFT.